GEOFF BENNETT: Vice President Kamala Harris and former President Donald Trump spent their weekends on the road, making their appeals to voters.

They each held rallies as concerns flooded the Internet from cybersecurity threats to false allegations involving artificial intelligence.

Laura Barron-Lopez has more.

LAURA BARRON-LOPEZ: It was a weekend marathon of rallies, both candidates on the campaign trail.

But for the third presidential election in a row, foreign interference has again cast an ominous shadow.

On Saturday, former President Trump claimed his campaign had been hacked and suggested Iran was to blame.

It stems from a Microsoft report one day earlier detailing a spearfishing incident from June, where Iranian military intelligence sent fake e-mails to a high-ranking official of a presidential campaign from a compromised e-mail account of a former senior adviser.

It's unclear what the breach achieved, but several media organizations say they have received anonymous e-mails with documents from the V.P.

vetting process.

The FBI is now investigating the hack.

But the incident didn't distract the former President Trump peddling lies about his opponent.

Trump reposted an image of a Harris rally in Detroit last week, falsely claiming she used artificial intelligence to fabricate the crowd size.

Photos and videos from the event showing thousands of supporters gathered at an airplane hangar easily disprove the conspiracy theory.

In response, the Harris campaign posted: "This is an actual photo of a 15,000-person crowd for Harris/Walz in Michigan."

Meanwhile, at a rally in Las Vegas, Harris made a new pitch to service workers, a key constituency in Nevada.

KAMALA HARRIS, Vice President of the United States (D) and U.S. Presidential Candidate: When I am president, we will continue our fight for working families of America... (CHEERING) (APPLAUSE) KAMALA HARRIS: ... including to raise the minimum wage and eliminate taxes on tips for service and hospitality workers.

(CHEERING) (APPLAUSE) LAURA BARRON-LOPEZ: It echoes a similar stance taken by her rival, a rare instance of political overlap, but one quickly rebutted by Trump, who accused Harris of -- quote -- "copying him," and said "The difference is, she won't do it."

Another target of Republican criticism, Harris' V.P.

pick, Minnesota Governor Tim Walz, and his military record, namely, a resurfaced clip from 2018 where Walz implied he had been deployed to a combat zone.

GOV.

TIM WALZ (D-MN), Vice Presidential Candidate: Those weapons of war that I carried in war.

LAURA BARRON-LOPEZ: The campaign said he misspoke, but Arkansas Senator Tom Cotton demanded more.

SEN. TOM COTTON (R-AR): I respect the service of all veterans, to include Tim Walz, who served for more than 20 years, but now even the campaign has acknowledged he's made past inconsistent statements about his service.

I think he should answer questions about those statements.

LAURA BARRON-LOPEZ: As for Trump's running mate, Ohio Senator J.D.

Vance made the rounds on Sunday shows.

Vance tried to walk back Trump's apparent willingness to ban abortion medication and said mass deportations should start with one million people.

SEN. J.D.

VANCE (R-OH), Vice Presidential Candidate: President Trump is absolutely right.

You cannot have a border unless you're willing to deport some people.

I think it's interesting that people focus on, well, how do you deploy 18 million people?

Let's start with one million.

LAURA BARRON-LOPEZ: But Vance argued, ultimately, it's Trump, not him, who voters care about.

SEN. J.D.

VANCE: Most people, 99 percent of the country, they don't vote on who the vice presidential nominee.

They're voting for Donald Trump or for Kamala Harris, not for J.D.

or Tim Walz.

LAURA BARRON-LOPEZ: Today, President Biden returned to the White House after spending the weekend in Delaware and expressing his support for the Harris ticket on CBS Sunday morning, his first sit-down interview since dropping out of the race last month.

JOE BIDEN, President of the United States: It's a great honor being president.

I think I have an obligation to the country to do what I -- the most important thing you can do, and that is we must, we must, we must defeat Trump.

LAURA BARRON-LOPEZ: Capping off a busy weekend with more campaigning ahead.

For the PBS "News Hour," I'm Laura Barron-Lopez.